Dozens of Tory MPs are preparing to rebel against the Government in order to prevent a no-deal Brexit, Theresa May has been warned.

Members of the Brexit Delivery Group, which is made up of Tory Leavers and Remainers, have told Number 10 they will back an attempt to extend Article 50 if the Prime Minister fails to pass a new deal in the Commons next week.

It is believed that at least 30 Conservative MPs - including some Cabinet ministers - are prepared to defy the Government whip in what would be a devastating blow to May's authority.

The Prime Minister is seeking changes to the Irish backstop - the insurance policy aimed at avoiding a hard border in Ireland - but so far talks in Brussels have failed to achieve a breakthrough.

Meanwhile, MPs are set to vote next week on an amendment in the name of Yvette Cooper and Oliver Letwin which would delay Brexit and effectively hand control of the process to Parliament.

In a letter to Tory chief whip Julian Smith, Brexit Delivery Group leaders Andrew Percy and Simon Hart say their members have become "deeply troubled" at the growing prospect of the UK quitting the EU without a deal.

They say: "The reputation for competence of both the party and the Government depends on our ability to deliver an orderly exit, in line with the existing timescale.

"Whilst we fully expect some changes to the backstop arrangements to be made by ministers in Brussels this week, there remains a chance that these will not satisfy some colleagues.

"Numerous members of our group have alerted us to their intention (should rejection of the deal look likely) to get behind amendments that are planned in the name of Oliver Letwin and others and which will have the twin effect of taking no deal off the table and delaying Brexit."

The letter, which has also been passed to The Telegraph, suggests that Tory MPs be given a free vote as a way of avoiding a mass rebellion.

"We wanted to alert you to the unease within our group and the way in which threats to next week's vote is pushing some members towards options which they have previously opposed but feel they have no option now but to consider," it says.

"To help manage this, we would recommend that the Government considers a free vote on these other options so that the will of the House can be properly tested."

Earlier this week, Cabinet members David Gauke, Amber Rudd, David Mundell and Greg Clark, warned the Prime Minister that they could also rebel unless she rules out no-deal before the 27 February votes.

Speculation has been mounting that May could head off the threat of ministerial resignations by putting a new Brexit deal to a so-called "meaningful vote" that day.

But she was dealt a blow last night when Jean-Claude Juncker said he was "not very optimistic" of avoiding a no-deal Brexit.